I think it is not a question of why Israel behaves like this, it is more a question of why the rest of the world lets it.
And I think the answer is in your question OP, most of the world sees Israel=Jews. The Jewish people have been persecuted for centuries to a greater or lesser extent have been / still are persecuted as a race not a religion. It didn't matter if you converted to another faith, you were still Jewish.
Some When Israel first became a state it was a place of safety for anyone who was Jewish regardless of their religious beliefs if that makes sense. Eg the Kibbutz system was based on communism and the first people to set them up were atheists.
I think in more recent years the people who have emigrated to Israel have tended to be more religious and that means people who believe their right to live on certain land is ordained by God, and, in some cases that they are superior to other humans.
As has already been stated, Israel is a democracy, and who are these people going to vote for? Politicians who agree with them.
Add to this the moderate Jewish people, some of whom have posted on MN in the last few days, or have written in Newspapers and actively distanced themselves from Israel and have no wish to live there and you get a situation where the world sees Israel as not just Jewish but particularly religious Jewish people and criticism of Israel becomes synonymous with antisemitism.
Not all Israelis are Jewish though, I believe 20-30% are of other faiths / ethnicities, but the world seems to ignore this.